Electronic organs include tone generating means connected to supply electric tone signals to keyers, and then to an audio system, while the keyers are activated by control signals obtained by electronically scanning a set of keyboard actuated switches. The operation of keyers by control signals derived by the electronic scanning of keyboard switches makes it possible to manipulate the control signals and thereby control the rate of attack, and/or decay, of the keyer activating signals.
A method commonly used to control the rate of attack or decay of a keyer control signal employs a capacitor-resistor network having a desired time constant. The keyer control signal is obtained by the voltage impressed upon the capacitor which will discharge at a controlled rate, as determined by the parameters of the network.
A further advantage of the technique of electronically scanning keyboard operated switches has been the ability to incorporate portions of the circuit of electronic organs within large scale integrated circuit chips. As the state of the art of electronic organs continues to mature, greater and greater portions of the circuit of electronic organs are produced by the method of large scale integration.
The method of controlling the keyer control signals by the use of a timing capacitor-resistor network, however, has required the continued use of capacitors external to integrated circuit chips because of the capacitor values required.
Therefore, it is an objective of the present invention to produce an organ keyer system in which the entire keyer control circuit can be manufactured on a single integrated circuit chip, without the necessity of any external timing capacitor.
It is a further objective of the present invention to develop an organ keyer system which can be inexpensively produced by the method of large scale integration.